These days, needle roller bearings, or needle bearings, are used on an engine's crankshaft-supporting parts or on large ends of connecting rods (conn rods), because the needle roller bearings have high load capacities even though their projected areas are small. A needle roller bearing includes a plurality of needle rollers, a cage for retaining the needle rollers, and an outer ring having a rolling surface on which the needle rollers roll. Another type of needle roller bearings may include a roller-and-cage assembly, which is a cage with needle rollers retained in advance, and an outer ring. These types of needle roller bearings exhibit low load resistance performance, but can be easily developed to rotate with low friction and low torque in comparison with sliding bearings without rolling elements. In addition, as it is relatively easy to develop the needle roller bearings that work with reduced amounts of lubricant oil, the needle roller bearings are often used as automotive parts, for example, a part of car engines.
Crankshafts, which are to be supported by the needle roller bearings, are provided with counterweights or the like at some midpoints in the axial direction, and therefore it is very difficult to mount bearing components on the crankshafts from the axial direction. To that end, an outer ring and cage are respectively split along the circumferential direction to prepare outer ring segments and cage segments that are then mounted on a shaft from the radial direction, more specifically, from the outer side of the shaft to attach a needle roller bearing.
Technologies of roller bearings used as automotive parts are disclosed in Japanese Unexamined Patent Application Publication No. 2002-195270 (PTL1), Japanese Registered Utility Model Publication No. 2584225 (PTL2), and Japanese Unexamined Patent Application Publication Nos. 2007-2914 (PTL3), 2009.19701 (PTL4), and 2009-19708 (PTL5).